Lens, lens blank, and eyewear

ABSTRACT

The lens comprises: a first transparent substrate that includes a diffraction region in which a plurality of convex strips and groove sections are formed in alternation in concentric circles; a second transparent substrate that faces the first transparent substrate; a liquid crystal layer disposed in a space present between the diffraction region and the second transparent substrate; and a first transparent electrode and a second transparent electrode that impress a voltage on the liquid crystal layer. The diffraction region comprises a first diffraction region and a second diffraction region that is disposed in at least part of a portion different from the first diffraction region. The space comprises: groove-shaped spaces present between the groove sections and the second transparent substrate; and a communicating space disposed between at least part of the convex shapes of the second diffraction region and the second transparent substrate, and communicating between neighboring groove-shaped spaces.

TECHNICAL FIELD

The present invention relates to a lens, a lens blank including thelens, and an eyewear including the lens.

BACKGROUND ART

In recent years, an electronic device worn by a user has been developed.Examples of the electronic device include an eyewear (for example,electronic glasses) including a region in which a focal length isswitchable by a voltage (for example, see PTL 1).

Each of lenses of the above-described eyewear includes a firsttransparent substrate including a first transparent electrode disposedon one of surfaces, a second transparent substrate including a secondtransparent electrode disposed on one of surfaces, and a liquid crystallayer disposed between the first transparent electrode and the secondtransparent electrode. More specifically, a diffraction region where aplurality of protruding strips are coaxially formed is located on atleast a part of the first transparent substrate. The liquid crystallayer is disposed at a position corresponding to the diffraction region.

For example, each of the lenses can be manufactured in such a mannerthat the first transparent substrate and the second transparentsubstrate are superimposed on each other and an adhesive is cured whilea liquid crystal material is provided to the diffraction region of thefirst transparent substrate (first transparent electrode) and theadhesive is provided to a region other than the diffraction region ofthe first transparent substrate. The liquid crystal material iscontained in spaces (hereinafter, groove spaces) existing among theadjacent protruding strips. As a result, the liquid crystal layer can bedisposed between the first transparent electrode and the secondtransparent electrode.

CITATION LIST Patent Literature

PTL 1

Japanese Unexamined Patent Application Publication (Translation of PCTApplication) No. 2010-532496

SUMMARY OF INVENTION Technical Problem

In a case where the above-described adjacent groove spaces do notcommunicate with one another in the diffraction region, the liquidcrystal material cannot move inside the adjacent groove spaces.Therefore, if the liquid crystal material is not appropriately providedover the entire diffraction region, the groove space not containing theliquid crystal material is generated between the first transparentsubstrate and the second transparent substrate.

An object of the present invention is to provide a lens for eyewear, inwhich the liquid crystal material is appropriately disposed between thefirst transparent substrate and the second transparent substrate, a lensblank including the lens, and an eyewear including the lens.

Solution to Problem

A lens for eyewear according to the present invention includes: a firsttransparent substrate that includes a diffraction region where aplurality of protruding strips and a plurality of grooves are coaxiallyand alternately formed; a second transparent substrate that faces thefirst transparent substrate in a predetermined direction; a liquidcrystal layer that is provided in a space between the diffraction regionand the second transparent substrate; and a first transparent electrodeand a second transparent electrode that apply a voltage to the liquidcrystal layer, in which: the diffraction region includes a firstdiffraction region and a second diffraction region that is located in atleast a part of a region different from the first diffraction region,and the space includes groove spaces and a communication space, thegroove spaces lying between the grooves and the second transparentsubstrate, the communication space lying between at least a part of theprotruding strips and the second transparent substrate in the seconddiffraction region and communicating between adjacent ones of the groovespaces with one another.

A lens blank according to the present invention includes: a blankportion; and the abovementioned lens formed integrally with the blankportion.

An eyewear according to the present invention includes theabovementioned lens; a frame that holds the lens; and a control sectionthat controls a voltage between the first transparent electrode and thesecond transparent electrode to control optical characteristics of theliquid crystal layer of the lens.

Advantageous Effects of Invention

The present invention makes it possible to provide a lens for eyewear,in which a liquid crystal material is appropriately disposed between afirst transparent substrate and a second transparent substrate, a lensblank including the lens, and an eyewear including the lens.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating an example of a configurationof electronic glasses according to Embodiment 1;

FIG. 2 is a block diagram illustrating an internal circuit of theelectronic glasses according to Embodiment 1;

FIG. 3 is a schematic cross-sectional view illustrating an example of aconfiguration of a lens;

FIG. 4A is a schematic plan view illustrating an example of a shape ofprotruding strips in a diffraction region;

FIG. 4B is a cross-sectional view taken along line B-B in FIG. 4A;

FIG. 4C is a cross-sectional view taken along line C-C in FIG. 4A;

FIG. 4D is an enlarged view of an X part in FIG. 4B;

FIG. 5 is a schematic diagram to explain the shape of the protrudingstrips;

FIG. 6A is a schematic cross-sectional view to explain a role of asecond diffraction region;

FIG. 6B is a schematic plan view to explain the role of the seconddiffraction region;

FIG. 7 is a diagram illustrating another example of a plan-view shape ofa diffraction region;

FIG. 8 is a diagram illustrating an example of a configuration of a lensblank;

FIG. 9 is a schematic diagram to explain a configuration of adiffraction region of a lens according to Embodiment 2;

FIG. 10 is a schematic diagram to explain a configuration of adiffraction region of a lens according to Embodiment 3;

FIG. 11 is a schematic diagram to explain a configuration of adiffraction region of a lens according to Embodiment 4;

FIG. 12 is a schematic diagram to explain a lens according to Embodiment5; and

FIG. 13 is a schematic diagram to explain a lens according to amodification of Embodiment 5.

DESCRIPTION OF EMBODIMENTS Embodiment 1

Embodiment 1 according to the present invention is described in detailbelow with reference to accompanying drawings. In the followingdescription, as a representative example of an eyewear according to thepresent invention, electronic glasses including lenses each including anelectrically active region where optical characteristics areelectrically controllable, are described.

[Configuration of Electronic Glasses]

FIG. 1 is a diagram illustrating a developed state of electronic glasses100 according to the present embodiment, and is a perspective viewillustrating an example of a configuration of electronic glasses 100.FIG. 2 is a block diagram illustrating an internal circuit of electronicglasses 100 according to the present embodiment. Electronic glasses 100include paired lenses 110, frame 120, control section 150 (see FIG. 2),and power supply 160. Frame 120 includes front 130 and paired temples140. Note that, in the following description, a portion where front 130is located is regarded as a front surface (front side) of electronicglasses 100. Note that, in FIG. 1, right-side temple 140 is illustratedin an exploded manner.

Further, in the following description for electronic glasses 100 andmembers constituting electronic glasses 100, “front-rear direction”,“width direction”, and “top-bottom direction” indicate respectivedirections of electronic glasses 100 in the developed state (in a stateillustrated in FIG. 1) at which a user can wear electronic glasses 100as glasses, unless otherwise noted. More specifically, the front-reardirection of electronic glasses 100 indicates a front-rear direction ofthe user when the user wears electronic glasses 100. Further, the widthdirection of electronic glasses 100 indicates a right-left direction ofthe user when the user wears electronic glasses 100. Furthermore, thetop-bottom direction of electronic glasses 100 indicates a verticaldirection of the user when the user wears electronic glasses 100.Moreover, in the following description for lenses 110 and membersconstituting lenses 110, “thickness direction” is coincident with thefront-rear direction of electronic glasses 100.

1) Lens

FIG. 3 is a schematic cross-sectional view illustrating an example of aconfiguration of each of lenses 110. FIG. 3 is a cross-sectional viewtaken along line A-A in FIG. 1. FIGS. 4A to 4D are schematic diagramseach illustrating an example of a shape of protruding strips 1172 indiffraction region 117. FIG. 4A is a plan view of diffraction region117, FIG. 4B is a cross-sectional view taken along line B-B in FIG. 4A,and FIG. 4C is a cross-sectional view taken along line C-C in FIG. 4A.FIG. 4D is an enlarged view of an X part in FIG. 4B. Note that, in FIG.3, FIG. 4B, and FIG. 4C, lens 110 (first transparent substrate 111) isillustrated while a curvature of lens 110 (first transparent substrate111) is regarded as zero.

Note that paired lenses 110 are formed so as to be right-leftsymmetrical when electronic glasses 100 are viewed from the front side(in other words, in planar view from front-rear direction), and includethe components same as each other. Accordingly, in the followingdescription, right-eye lens 110 of electronic glasses 100 is described,and description of the components of left-eye lens 110 is omitted.

Lens 110 includes first region (electrically active region) 1101 inwhich a focal length (diopter) is switchable by a voltage, and secondregion 1102 that is located in a region other than first region 1101.Lens 110 may be a spherical lens or an aspherical lens. A shape of lens110 can be appropriately adjusted based on desired optical power.

A shape, a size, and a position of first region 1101 can beappropriately designed based on the size, application, and the like oflens 110. Examples of the application of lens 110 include a bifocallens, a progressive addition lens for near/intermediate bifocals, and aprogressive addition lens for near/near bifocals. Further, asillustrated in FIG. 1, first region 1101 is located on side lower than acenter part of lens 110 when lens 110 is viewed from the front side (inother words, in planar view from front-rear direction).

As illustrated in FIG. 3, first region 1101 includes first transparentsubstrate 111, first transparent electrode 112, liquid crystal layer113, second transparent electrode 114, and second transparent substrate115 in order from the rear side (lower side in FIG. 3). Second region1102 includes first transparent substrate 111, first transparentelectrode 112, bonding layer 116, second transparent electrode 114, andsecond transparent substrate 115 in order from the rear side. Thecomponents each have translucency to visible light.

First transparent substrate 111 is disposed on the rear side (user side)of lens 110 in electronic glasses 100. First transparent substrate 111is curved so as to protrude toward the front side of electronic glasses100. A curvature and a shape of first transparent substrate 111 can beappropriately adjusted based on desired optical power.

Although the detail is described below, first transparent substrate 111includes diffraction region 117 located in a region corresponding tofirst region 1101. In the present embodiment, first region 1101 iscoincident with diffraction region 117. Diffraction region 117 includesspherical-crown-shaped protrusion 1171 at a center part on one surface(surface on front side).

Protrusion 1171 has a circular shape in a planar view from a thicknessdirection (front-rear direction). In the following, a structure ofdiffraction region 117 in a plan-view shape from the thickness directionis described. In the present embodiment, a center position of protrusion1171 and a center position of diffraction region 117 (first region 1101)are overlapped with each other.

Diffraction region 117 includes plurality of annular protruding strips1172 outside protrusion 1171. Diffraction region 117 includes pluralityof annular grooves 1179 (see FIG. 4B and FIG. 4C) among adjacentprotruding strips 1172. In other words, diffraction region 117 includesplurality of protruding strips 1172 and plurality of grooves 1179 thatare coaxially and alternately formed. Ridge lines of protruding strips1172 are coaxially provided around the center of protrusion 1171 (inpresent embodiment, also center of diffraction region 117). The ridgelines of protruding strips 1172 are increased in diameter as separatingfrom protrusion 1171 (namely, toward outside).

In contrast, plurality of protruding strips 1172 are decreased indistance between the ridge lines of adjacent protruding strips 1172 asseparating from protrusion 1171 (namely, toward outside). Note that eachof protruding strips 1172 may have an annular shape continuous over theentire circumference in a circumferential direction, or may have apartial annular shape. Further, the center position of protrusion 1171and the center position of diffraction region 117 (first region 1101)may be different configuration from each other in a planar view from thethickness direction (front-rear direction) (see FIG. 11 to FIG. 13).

Note that, in the present specification, “outside” in the descriptionfor diffraction region 117 indicates a position farther from the centerof diffraction region 117 along a direction orthogonal to an opticalaxis of light entering lens 110 from the front side of electronicglasses 100 in a state where lens 110 is used (in a state where lens 110is assembled in electronic glasses 100 and is used). In other words, inthe description for diffraction region 117, “outside” indicates aposition farther from the center position of diffraction region 117 (inpresent embodiment, center of protrusion 1171) in a planar view (seeFIG. 4A) from the thickness direction (front-rear direction). Incontrast, in the description for diffraction region 117, “inside”indicates a position closer to the center position of diffraction region117 (in present embodiment, center of protrusion 1171) in a planar view(see FIG. 4A) from the thickness direction (front-rear direction).

The shape of protrusion 1171 and protruding strips 1172 can beappropriately adjusted, based on desired optical power in diffraction ofthe light entered from the front side of electronic glasses 100.Although the detail is described below, the shape of protruding strips1172 can be appropriately adjusted in terms of filling of a liquidcrystal material in manufacture of lens 110 in the present embodiment.Examples of the shape of protrusion 1171 and protruding strips 1172include a Fresnel lens shape. A part or all of protrusion 1171 andprotruding strips 1172 may be formed in a Fresnel lens shape.

The material of first transparent substrate 111 is not particularlylimited as long as the material has translucency. For example, as thematerial of first transparent substrate 111, a well-known material usedas a material of a lens can be used. Examples of the material of firsttransparent substrate 111 include glass and a resin. Examples of theresin include polymethyl methacrylate, polycarbonate, polydiethyleneglycol bis(allyl carbonate), and polystyrene.

First transparent electrode 112 and second transparent electrode 114 arepaired transparent electrodes having translucency. First transparentelectrode 112 and second transparent electrode 114 are disposed in atleast a range (first region 1101) where first transparent electrode 112and second transparent electrode 114 can apply a voltage to liquidcrystal layer 113, and may not be disposed in second region 1102.

As illustrated in FIG. 3, first transparent electrode 112 is disposed atleast between diffraction region 117 of first transparent substrate 111and liquid crystal layer 113. In other words, first transparentelectrode 112 is disposed over a region corresponding to at leastdiffraction region 117 on a surface (top surface in FIG. 3, and alsoreferred to as front surface) of first transparent substrate 111 onsecond transparent substrate 115 side. Further in other words, firsttransparent electrode 112 is disposed in a region overlapped with atleast diffraction region 117 in the thickness direction (top-bottomdirection in FIG. 3) on the front surface of first transparent substrate111. In the present embodiment, first transparent electrode 112 isdisposed over the substantially entire front surface of firsttransparent substrate 111.

Second transparent electrode 114 is disposed between liquid crystallayer 113 and second transparent substrate 115. In other words, secondtransparent electrode 114 is disposed in a region overlapped with atleast diffraction region 117 in the thickness direction, on a surface(bottom surface in FIG. 3, also referred to as rear surface) of secondtransparent substrate 115 on first transparent substrate 111 side. Morespecifically, second transparent electrode 114 is disposed so as to facefirst transparent electrode 112 positioned on at least diffractionregion 117 in the thickness direction. In the present embodiment, secondtransparent electrode 114 is disposed over the substantially entire rearsurface of second transparent substrate 115.

The material of first transparent electrode 112 and second transparentelectrode 114 is not particularly limited as long as the material hasdesired translucency and desired electroconductivity. Examples of thematerial of first transparent electrode 112 and second transparentelectrode 114 include indium tin oxide (ITO) and zinc oxide (ZnO). Thematerial of first transparent electrode 112 and the material of secondtransparent electrode 114 may be the same as or different from eachother.

Liquid crystal layer 113 is disposed in a space between firsttransparent substrate 111 and second transparent substrate 115. Liquidcrystal layer 113 may be directly sandwiched between first transparentsubstrate 111 and second transparent substrate 115. Alternatively,liquid crystal layer 113 may be disposed between one component disposedbetween first transparent substrate 111 and liquid crystal layer 113 andthe other component disposed between liquid crystal layer 113 and secondtransparent substrate 115. In the present embodiment, liquid crystallayer 113 is disposed between first transparent electrode 112 and secondtransparent electrode 114. Liquid crystal layer 113 has a shapecorresponding to plurality of protruding strips 1172 of diffractionregion 117 described below.

Liquid crystal layer 113 is configured such that a refractive indexthereof is varied based on presence/absence of voltage application.Although the detail is described below, for example, the refractiveindex of liquid crystal layer 113 can be adjusted so as to besubstantially equal to a refractive index of first transparent substrate111 and a refractive index of second transparent substrate 115 in astate where no voltage is applied to liquid crystal layer 113. Further,the refractive index of liquid crystal layer 113 can be adjusted so asto be different from the refractive index of first transparent substrate111 and the refractive index of second transparent substrate 115 in astate where a voltage is applied to liquid crystal layer 113.

Liquid crystal layer 113 contains a liquid crystal material. Anorientation state of the liquid crystal material when the voltage isapplied and an orientation state of the liquid crystal material when novoltage is applied are different from each other. The liquid crystalmaterial can be appropriately selected based on the refractive index offirst transparent substrate 111 and the refractive index of secondtransparent substrate 115. For example, the liquid crystal materialincludes cholesteric liquid crystal or nematic liquid crystal.

Second transparent substrate 115 is disposed on first transparentsubstrate 111 with first transparent electrode 112, liquid crystal layer113, and second transparent electrode 114 in between. Second transparentsubstrate 115 is disposed on the front side of lens 110 in electronicglasses 100. Second transparent substrate 115 is also curved so as toprotrude toward the front side of electronic glasses 100. A curvature ofsecond transparent substrate 115 corresponds to the curvature of firsttransparent substrate 111. Examples of the material of secondtransparent substrate 115 are the same as the examples of the materialof first transparent substrate 111.

Bonding layer 116 is disposed between first transparent substrate 111and second transparent substrate 115 in second region 1102, and bondsfirst transparent substrate 111 and second transparent substrate 115 toeach other. In a case where first transparent electrode 112 and secondtransparent electrode 114 are also disposed in second region 1102,bonding layer 116 is disposed between first transparent electrode 112and second transparent electrode 114 disposed in second region 1102.Further, bonding layer 116 also has a function to seal the liquidcrystal material constituting liquid crystal layer 113.

Bonding layer 116 is formed of a cured product of an adhesive. Amaterial of the adhesive is not particularly limited as long as thematerial has desired translucency and can appropriately bond firsttransparent substrate 111 and second transparent substrate 115. Anadhesive having a desired refractive index can be selected in order toadjust the optical power of lens 110.

Lens 110 may further include other components each having translucencyas necessary. Examples of the other components include an insulatinglayer and an orientated film.

The insulating layer prevents conduction between first transparentelectrode 112 and second transparent electrode 114 through liquidcrystal layer 113. For example, the insulating layer is disposed betweenfirst transparent electrode 112 and liquid crystal layer 113 and betweenliquid crystal layer 113 and second transparent electrode 114. As amaterial of the insulating layer, a well-known material that hastranslucency and is used as an insulating layer can be used. Examples ofthe material of the insulating layer include silicon dioxide.

The orientated film controls the orientation state of the liquid crystalmaterial in liquid crystal layer 113. For example, the orientated filmis disposed between first transparent electrode 112 and liquid crystallayer 113 and between liquid crystal layer 113 and second transparentelectrode 114. As a material of the orientated film, a well-knownmaterial used as the orientated film for the liquid crystal material canbe used. Examples of the material of the orientated film includepolyimide.

(Diffraction Region)

Next, diffraction region 117 is described. The size and the plan-viewshape (shape of diffraction region 117 illustrated in FIG. 4A, andhereinafter simply referred to as plan-view shape) from the thicknessdirection of diffraction region 117 correspond to first region 1101. Thesize and the plan-view shape of diffraction region 117 can beappropriately adjusted based on an area of a human visual field. Forexample, diffraction region 117 is preferably formed such that a lengthin a width direction (right-left direction in FIG. 4A) is larger than alength in the top-down direction. Note that, in the presentspecification, the plan-view shape of diffraction region 117 indicates ashape when diffraction region 117 is viewed from a position on theoptical axis of the light entering lens 110 on the front side ofelectronic glasses 100.

As illustrated in FIG. 4A, the plan-view shape of diffraction region 117is a so-called barrel shape. In other words, in the plan-view shape,outer edge α (see FIG. 4A) of diffraction region 117 includes two pairsof opposite sides (pair of first outer edge element α₁ and second outeredge element α₂ and pair of third outer edge element α₃ and fourth outeredge element α₄ in FIG. 4A). The opposite sides of one of two pairs ofopposite sides (first outer edge element α₁ and second outer edgeelement α₂ in FIG. 4A) are opposite sides extending along a short-axisdirection (top-bottom direction in FIG. 4A) of diffraction region 117and are arcs.

In the present embodiment, first outer edge element α₁ and second outeredge element α₂ are a part of a circle around a centroid (center)position (also center of protrusion 1171) of diffraction region 117(first region 1101), in the plan-view shape. The opposite sides of theother of the two pairs of opposite sides (third outer edge element α₃and fourth outer edge element α₄ in FIG. 4A) are opposite sidesextending along a long-axis direction (right-left direction in FIG. 4A)of diffraction region 117.

Each of third outer edge element α₃ and fourth outer edge element α₄connects both ends of the one pair of opposite sides. Each of thirdouter edge element α₃ and fourth outer edge element α₄ may be a straightline or a curved line. In a case where each of third outer edge elementα₃ and fourth outer edge element α₄ is a curved line, each of thirdouter edge element α₃ and fourth outer edge element α₄ is preferably acurved line protruding to the outside of diffraction region 117 in orderto enhance visibility of the user. In the present embodiment, asillustrated in FIG. 4A, each of third outer edge element α₃ and fourthouter edge element α₄ is a curved line protruding to the outside ofdiffraction region 117. Note that first outer edge element α₁ and secondouter edge element α₂ in FIG. 4A may extend along the long-axisdirection and third outer edge element α₃ and fourth outer edge elementα₄ may extend along the short-axis direction.

In other words, first outer edge element α1 and second outer edgeelement α₂ of outer edge α of diffraction region 117 are opposed to eachother in a first direction (for example, right-left direction in FIG.4A) orthogonal to the optical axis direction (direction perpendicular topaper surface of FIG. 4A). More specifically, first outer edge elementα₁ has a shape following one protruding strip 1172 a that is provided onthe outermost side on one side (right side in FIG. 4A) of diffractionregion 117 in the first direction. In other words, a curvature radius offirst outer edge element α₁ is equal to or slightly larger than acurvature radius of protruding strip 1172 a.

Note that, in the present embodiment, first outer edge element α₁ iscoincident with protruding strip 1172 a. Accordingly, the curvatureradius of first outer edge element α₁ is equal to the curvature radiusof protruding strip 1172 a. On the other hand, second outer edge elementα₂ is coincident with one protruding strip 1172 b that is provided onthe outermost side on the other side (left side in FIG. 4A) ofdiffraction region 117 in the first direction. Accordingly, a curvatureradius of second outer edge element α₂ is equal to a curvature radius ofprotruding strip 1172 b.

Note that first outer edge element α₁ and second outer edge element α₂may be respectively positioned on the outside of protruding strip 1172 aand protruding strip 1172 b. In other words, protruding-strip absentpart 1176 where no protruding strip is formed as illustrated in FIG. 4Cmay exist between protruding strip 1172 a and first outer edge elementα₁ and between protruding strip 1172 b and second outer edge element α₂.In this case, the curvature radius of first outer edge element α₁ andthe curvature radius of second outer edge element α₂ are respectivelyslightly larger than the curvature radius of protruding strip 1172 a andthe curvature radius of protruding strip 1172 b.

On the other hand, third outer edge element c and fourth outer edgeelement α₄ are opposed to each other in second direction (for example,top-bottom direction in FIG. 4A) orthogonal to the optical axisdirection and the above-described first direction, in the plan-viewshape. Such third outer edge element α₃ and fourth outer edge element α₄intersect with plurality of protruding strips 1172. Accordingly,plurality of protruding strips 1172 intersecting with third outer edgeelement α₃ is broken off at the position of third outer edge element α₃.On the other hand, plurality of protruding strips 1172 intersecting withfourth outer edge element α₄ is broken off at the position of fourthouter edge element α₄.

In addition, third outer edge element α₃ and fourth outer edge elementα₄ also intersect with groove spaces 1175 (see FIG. 4B and FIG. 4C)among adjacent protruding strips 1172 (namely, between grooves 1179 andsecond transparent substrate 115). Accordingly, groove spaces 1175intersecting with third outer edge element α₃ are broken off at theposition of third outer edge element α₃. On the other hand, groovespaces 1175 intersecting with fourth outer edge element α₄ are brokenoff at the position of fourth outer edge element α₄.

Groove spaces 1175 broken off at the position of third outer edgeelement α₃ are open to an external space existing on the outside ofthird outer edge element α₃. On the other hand, groove spaces 1175broken off at the position of fourth outer edge element α₄ are open toan external space existing on the outside of fourth outer edge elementα₄. In other words, broken-off groove spaces 1175 and the external spacecommunicate with each other in a state where the liquid crystal materialconstituting liquid crystal layer 113 is movable.

Note that relationship between the above-described first direction andthe above-described second direction is not limited to theabove-described case. The above-described first direction and theabove-described second direction may be rotated by a predetermined anglearound the optical axis passing through center O₁ (see FIG. 4A) ofdiffraction region 117 while maintaining orthogonal relationship.Further, the above-described first direction and the above-describedsecond direction may not be orthogonal to each other.

FIG. 5 is a schematic cross-sectional view of diffraction region 117taken along line B-B in FIG. 4A. The shape of protruding strips 1172 isdescribed below with reference to FIG. 5. In FIG. 5, first transparentsubstrate 111 and second transparent substrate 115 are illustrated whilethe curvature of first transparent substrate 111 and curvature of secondtransparent substrate 115 are regarded as zero. Note that, in FIG. 5,reference numeral d₁ indicates a distance between each of the ridgelines of protruding strips 1172 and second transparent substrate 115 infirst diffraction region 1173. Reference numeral d₂ indicates a distancebetween each of the ridge lines of protruding strips 1172 and secondtransparent substrate 115 in second diffraction region 1174. Referencenumeral d₃ indicates a distance between each of valley lines amongadjacent protruding strips 1172 and second transparent substrate 115.Reference numeral w indicates a distance between an outer edge of seconddiffraction region 1174 and an inner edge of second diffraction region1174 (width of second diffraction region 1174).

As illustrated in FIGS. 4B and 4C and FIG. 5, diffraction region 117includes first diffraction region 1173 and second diffraction region1174. First diffraction region 1173 is located at a position includingthe center part of diffraction region 117 in a planar view from thethickness direction.

In the present specification, “first diffraction region 1173” indicatesa region where protruding strips 1172 are formed such that liquidcrystal layer 113 (liquid crystal material) is not substantiallydisposed between the ridge lines of protruding strips 1172 and secondtransparent substrate 115. In other words, first diffraction region 1173indicates a region where protruding strips 1172 are formed such that thecomponents (in present embodiment, first transparent electrode 112 andsecond transparent electrode 114) disposed on both sides of liquidcrystal layer 113 come into contact with or come close to each otherbetween the ridge lines of protruding strips 1172 and second transparentsubstrate 115. In a state where “the components come close to eachother”, it is sufficient for the components to come close to each otherto a degree enough to prevent the liquid crystal material constitutingliquid crystal layer 113 from sufficiently moving between the ridgelines of protruding strips 1172 and second transparent substrate 115over the ridge lines. In a case where the components each haveinsulation property, the components may be in contact with each other.

Further in other words, first diffraction region 1173 is a region wherecommunication space 1177 (see FIG. 4D) which communicates between groovespaces 1175 located on both sides of each of protruding strips 1172 soas to allow liquid crystal layer 113 (liquid crystal material) to moveis not provided between the ridge lines of protruding strips 1172 andsecond transparent substrate 115. More specifically, in the presentembodiment, first diffraction region 1173 is a region inside solid lineβ of diffraction region 117 in FIG. 4A in a planar view (in a stateillustrated in FIG. 4A) from the thickness direction. Solid line β is aninner end edge of second diffraction region 1174 described below.

On the other hand, “second diffraction region 1174” indicates a regionwhere protruding strips 1172 are formed such that liquid crystal layer113 (liquid crystal material) is disposed between the ridge lines ofprotruding strips 1172 and second transparent substrate 115. In otherwords, second diffraction region 1174 indicates a region whereprotruding strips 1172 are formed such that the components disposed onboth sides of liquid crystal layer 113 are separated from each otherbetween the ridge lines of protruding strips 1172 and second transparentsubstrate 115. Further in other words, second diffraction region 1174 isa region where communication space 1177 (see FIG. 4D) which communicatesbetween groove spaces 1175 located on both sides of each of protrudingstrips 1172 so as to allow liquid crystal layer 113 (liquid crystalmaterial) to move is provided between the ridge lines of protrudingstrips 1172 and second transparent substrate 115.

Second diffraction region 1174 is located at least a part on the outsideof first diffraction region 1173 in diffraction region 117. In thepresent embodiment, second diffraction region 1174 is located on anouter edge part of diffraction region 117 (predetermined range includingouter edge α of diffraction region 117). More specifically, in thepresent embodiment, second diffraction region 1174 is a region insideouter edge α and outside solid line β in FIG. 4A of diffraction region117 in the plan-view shape (in a state illustrated in FIG. 4A).

Second diffraction region 1174 may be continuously located over theentire circumference or may not be located over the entire circumferenceon the outside of first diffraction region 1173 (in present embodiment,outer edge part of diffraction region 117). The example in which seconddiffraction region 1174 is continuously provided over the entirecircumference on the outside of first diffraction region 1173 indiffraction region 117 corresponds to the present embodiment. Incontrast, the example in which second diffraction region 1174 isprovided in a part of the outside of first diffraction region 1173 indiffraction region 117 corresponds to Embodiments 2 to 5 describedbelow.

Although the detail is described below, second diffraction region 1174is preferably located over the entire circumference on the outer edgepart of diffraction region 117 in order to evenly provide the liquidcrystal material on the outer edge part of diffraction region 117. Thesize of second diffraction region 1174 can be appropriately adjustedbased on the size of lens 110 within a range in which the effects of thepresent embodiment are achievable. For example, distance w is set to 0.1mm to 2 mm.

Note that, as illustrated in FIG. 4C and FIG. 5, for example,protruding-strip absent part 1176 where no protruding strip 1172 isformed may be provided on the outside of second diffraction region 1174in diffraction region 117. Protruding-strip absent part 1176 contributesto prevention of flowing-out of the liquid crystal material (namely,exerts sealing function). Protruding-strip absent part 1176 may beprovided on the outside of second diffraction region 1174 so as tosurround the entire circumference of second diffraction region.Protruding-strip absent part 1176 may include planar part 1178 asillustrated in FIG. 4C on a front end. Such a configuration is moreeffective to prevent the liquid crystal material from flowing out.Further, as illustrated in FIG. 4B, the ridge line of protruding strip1172 a on the outermost side in second diffraction region 1174 may belocated at a position (upper side in FIG. 4B) close to secondtransparent substrate 115 as compared with the positions of the ridgelines of the other protruding strips 1172 constituting seconddiffraction region 1174. Such a configuration also contributes toprevention of flowing-out of the liquid crystal material.

Although the detail is described below, the shape of protruding strips1172 in second diffraction region 1174 is not particularly limited aslong as the liquid crystal material can appropriately move over theridge lines through a gap (communication space 1177 in FIG. 4D) betweenthe ridge lines of protruding strips 1172 and second transparentsubstrate 115, in manufacture of lens 110. From such perspectives,protruding strips 1172 are formed such that distance d₂ is larger thandistance d₁.

To appropriately dispose the liquid crystal material to the outer edgepart of diffraction region 117, at least a part of a virtual surface(see alternate long and two short dashes line P₁ in FIG. 4D) formed byconnecting the ridge lines of protruding strips 1172 in seconddiffraction region 1174 preferably has a groove shape. The shape of atleast a part of the virtual surface preferably has the groove shapeextending along an outer periphery of lens 110. In addition, of theouter periphery of lens 110, the shape of at least a part of the virtualsurface may have the groove shape extending along paired opposite sidescrossing the horizontal direction. The “horizontal direction” usedherein indicates the horizontal direction in the right-left direction ofelectronic glasses 100 and in a direction orthogonal to the optical axisof the light entering lens 110, in the state where lens 110 is used (ina state where lens 110 is assembled in electronic glasses 100 and isused).

From the above-described perspectives, the virtual surface formed byconnecting the ridge lines of adjacent protruding strips 1172 in seconddiffraction region 1174 at the shortest distance preferably has thegroove shape (see alternate long and two short dashes line P₁ in FIG.4D) recessed with respect to second transparent substrate 115. Note thatalternate long and two short dashes line P₁ in FIG. 4D indicates across-sectional shape of the above-described virtual surface in a casewhere second diffraction region 1174 is cut on a surface that passesthrough a normal of protruding strips 1172 and is parallel to theoptical axis direction, in a planar view (in a state illustrated in FIG.4A) from the thickness direction.

In the present embodiment, a middle part of virtual surface P₁ isfarthest from second transparent substrate 115. Further, virtual surfaceP₁ comes close to second transparent substrate 115 as it goes from themiddle part to the inner end edge (namely, toward center of diffractionregion 117). In addition, virtual surface P₁ comes close to secondtransparent substrate 115 as it goes from the middle part to the outerend edge (namely, as separating from center of diffraction region 117).

Moreover, to appropriately dispose the liquid crystal material to theouter edge part of diffraction region 117, distance d₁ between the ridgeline of protruding strip 1172 located on the outer edge of firstdiffraction region 1173 and second transparent substrate 115 and maximumvalue (d_(2max)) of distance d₂ between each of protruding strips 1172and second transparent substrate 115 in second diffraction region 1174are preferably different by 0.1 μm to 2 μm.

To suppress drastic change of a focal length at a boundary between firstregion 1101 and second region 1102 to improve visibility of the user, atleast a part of plurality of protruding strips 1172 formed on the outeredge part of diffraction region 117 is preferably provided such thatdistance d₃ between each of the valley lines among adjacent protrudingstrips 1172 and second transparent substrate 115 is gradually reducedtoward the outer edge α (see FIG. 4A) of diffraction region 117.

In the following, a region where distance d₃ is gradually reduced towardthe outer edge of diffraction region 117 is also referred to as a blendzone. The blend zone is located in at least a part of second diffractionregion 1174. The above-described blend zone may be located over both offirst diffraction region 1173 and second diffraction region 1174. Inaddition, the above-described blend zone may be located over the entirecircumference or may not be located over the entire circumference on theouter edge part of diffraction region 117.

In terms of visibility of the user, the above-described blend zone ispreferably formed on an upper end part (also referred to as one end partin first direction) and a lower end part (also referred to as other endpart in first direction) of diffraction region 117. In the presentembodiment, the above-described blend zone is formed only on the upperend part and the lower end part of diffraction region 117 and on theouter edge part of second diffraction region 1174 (see and compare FIG.4B and FIG. 4C).

(Method of Manufacturing Lens)

Lens 110 can be manufactured by, for example, the followingmanufacturing method. First, first transparent substrate 111 and secondtransparent substrate 115 are prepared. First transparent substrate 111and second transparent substrate 115 can be manufactured by, forexample, injection molding. Next, first transparent electrode 112 isformed on first transparent substrate 111, and second transparentelectrode 114 is formed on second transparent substrate 115.

Examples of a method of forming first transparent electrode 112 on firsttransparent substrate 111 and examples of a method of forming secondtransparent electrode 114 on second transparent substrate 115 eachinclude a vacuum deposition method and sputtering. Next, the liquidcrystal material is provided on diffraction region 117 of firsttransparent substrate 111 provided with first transparent electrode 112as well as the adhesive is provided to a part other than diffractionregion 117 of first transparent substrate 111. Second transparentsubstrate 115 provided with second transparent electrode 114 is disposedon first transparent substrate 111 while the liquid crystal material andthe adhesive are disposed on first transparent substrate 111. Finally,the adhesive is cured. As a result, lens 110 is manufactured.

FIGS. 6A and 6B are schematic diagrams to explain a role of seconddiffraction region 1174. In FIGS. 6A and 6B, illustration of theconfiguration other than first transparent substrate 111 is omitted.

A case where diffraction region 117 does not include second diffractionregion 1174 (only include first diffraction region 1173) is considered.In this case, since the spaces among adjacent protruding strips 1172 donot communicate with one another through the gap between the ridge linesof protruding strips 1172 and second transparent substrate 115, theliquid crystal material cannot move among the spaces over the ridgelines. Accordingly, the outer edge part (for example, upper end part,lower end part, left end part, and right end part of diffraction region117 in FIG. 4A) of diffraction region 117 where a supply amount of theliquid crystal material easily becomes insufficient may not beappropriately filled with the liquid crystal material.

In the present embodiment, however, diffraction region 117 includessecond diffraction region 1174 and protruding strips 1172 are configuredsuch that distance d₂ is larger than distance d₁ (see FIG. 5). As aresult, the gap (communication space 1177) through which the liquidcrystal material can move over the ridge lines is formed between theridge lines of protruding strips 1172 and second transparent substrate115. Accordingly, when first transparent substrate 111 and secondtransparent substrate 115 are superimposed on each other, the liquidcrystal material can move among the adjacent spaces through theabove-described gap (see thick arrow in FIG. 6A). As a result, theliquid crystal material can be appropriately disposed even on the outeredge part of diffraction region 117.

Now, the case where diffraction region 117 does not include seconddiffraction region 1174 (only includes first diffraction region 1173) isconsidered again. At the outer edge part (upper end part and lower endpart in FIG. 4A) of diffraction region 117, the spaces (groove spaces1175) among the adjacent protruding strips 1172 communicate with thespace (space between first transparent substrate 111 and secondtransparent substrate 115) outside diffraction region 117. Accordingly,in the case where diffraction region 117 does not include seconddiffraction region 1174, the liquid crystal material can flow only inthe direction along groove spaces 1175 and may flow out to the outsideof diffraction region 117 (see thin dashed arrow in FIG. 6B).

In the present embodiment, however, groove spaces 1175 in seconddiffraction region 1174 communicate with one another through theabove-described gap (communication space 1177). Accordingly, the liquidcrystal material can move among adjacent groove spaces 1175 throughcommunication space 1177 (see thick arrow in FIG. 6B). In other words, aflow path of the liquid crystal material is separately formed, and theliquid crystal material is prevented from flowing into the outside ofdiffraction region 117. As a result, the liquid crystal material can beappropriately disposed even on the outer edge part of diffraction region117.

As described above, in the present embodiment, it is possible toappropriately provide the liquid crystal material and to appropriatelydispose liquid crystal layer 113 even on the outer edge part ofdiffraction region 117. To appropriately dispose liquid crystal layer113 over the entire circumference of diffraction region 117, seconddiffraction region 1174 is preferably located over the entirecircumference on the outer edge part of diffraction region 117.

2) Front

As illustrated in FIG. 1, front 130 holds paired lenses 110. Front 130includes paired rims 131 supporting respective paired lenses 110, andbridge 132 that connects paired rims 131 in the width direction. Theshape of each of rims 131 corresponds to the shape of each of lenses110. Bridge 132 includes paired nose pads 133 that can come into contactwith a nose of the user. As illustrated in FIG. 1, wiring 10 thatelectrically connects first transparent electrode 112 of each of lenses110 and control section 150 described below, and electrically connectssecond transparent electrode 114 of each of lenses 110 and controlsection 150 is disposed inside front 130.

A material of front 130 is not particularly limited. As the material offront 130, a well-known material used as a material of a front ofglasses can be used. Examples of the material of front 130 includepolyamide, acetate, carbon, celluloid, polyetherimide, and urethane.

3) Temple

Paired temples 140 are formed so as to be substantially right-leftsymmetrical in electronic glasses 100, and includes the components sameas each other. Accordingly, in the following description, right-side(one side in width direction) temple 140 is described, and thecomponents of left-side (other side in width direction) temple 140 aredenoted by the same reference numerals, and description of thecomponents is omitted.

A front end part of temple 140 is connected to front 130. For example,temple 140 rotatably engages with corresponding rim 131 of front 130.

As illustrated in FIG. 1, temple 140 includes housing 141 and detectionsection 142.

Housing 141 configures an outer shape of temple 140. Housing 141contains detection section 142 and control section 150. Housing 141extends along one direction. Housing 141 includes a protruding strip ona left-side surface (outside surface of electronic glasses 100). Aposition on the left-side surface of housing 141 corresponding todetection section 142 has a planar shape. Accordingly, the user caneasily recognize the position where detection section 142 is located.Further, a surface shape on a right-side surface of housing 141 (insidesurface of electronic glasses 100) is a planar shape.

A material of housing 141 is not particularly limited. As the materialof housing 141, a well-known material used as a material of a temple ofglasses can be used. Examples of the material of housing 141 are same asthe examples of the material of front 130.

Detection section 142 includes, for example, an electrostaticcapacitance detection pad. As the detection pad, a well-known detectionpad used as a touch sensor can be used. Detection section 142 detectschange of an electrostatic capacitance caused by contact when an object(finger of user or the like) comes into contact with the position ofhousing 141 corresponding to detection section 142.

4) Control Section

Control section 150 is electrically connected to the detection pad ofdetection section 142 and the electrodes (first transparent electrode112 and second transparent electrode 114) of lenses 110 through wiring10. When detection section 142 detects contact of the object, controlsection 150 applies a voltage to paired lenses 110 or stops applicationof the voltage to paired lenses 110, thereby switching the focal length(diopter) of first region 1101 (see FIG. 2). Control section 150includes a control circuit that controls, for example, driving of thedetection pad, detection of change of the electrostatic capacitance inthe detection pad, and application of the voltage between firsttransparent electrode 112 and second transparent electrode 114 (inpresent embodiment, liquid crystal layer 113) of each of lenses 110. Forexample, control section 150 is mounted on detection section 142 whilebeing connected to the detection pad so as to receive a detection resultabout change of the electrostatic capacitance in the detection pad.

5) Power Supply

Power supply 160 supplies power to detection section 142 and controlsection 150 (see FIG. 2). In the present embodiment, power supply 160 isa chargeable battery pack that is detachably held by the other end part(rear end part) of each of temples 140. Examples of power supply 160include a nickel-hydrogen rechargeable battery.

[Operation of Electronic Glasses]

Subsequently, an example of operation of electronic glasses 100 isdescribed. First, a state (off state) where a voltage is not applied toliquid crystal layer 113 of electronic glasses 100 is described. In theoff state, the refractive index of liquid crystal layer 113 and therefractive index of each of first transparent substrate 111 and secondtransparent substrate 115 are substantially equal to each other in firstregion 1101 of each of lenses 110. Therefore, the lens effect derivedfrom liquid crystal layer 113 does not occur. Accordingly, in each oflenses 110, the focal length (diopter) of first region 1101 and thefocal length (diopter) of second region 1102 become substantially equalto each other.

When the position of housing 141 corresponding to detection section 142is contacted by an object (for example, finger of user) as a conductor,change of the electrostatic capacitance caused by the contact isdetected by the detection pad of detection section 142. The detectionresult of the contact is transmitted to control section 150. When thecontact of the object is detected in the off state, control section 150applies a voltage to liquid crystal layer 113 of each of lenses 110.

As a result, orientation of the liquid crystal material in liquidcrystal layer 113 is changed and the refractive index of liquid crystallayer 113 is changed (on state). In the on state, the refractive indexof liquid crystal layer 113 and the refractive index of each of firsttransparent substrate 111 and second transparent substrate 115 aredifferent from each other. Therefore, the lens effect derived fromliquid crystal layer 113 occurs in first region 1101. This makes itpossible to change the focal length (diopter) of first region 1101.

In the on state, when the position of housing 141 corresponding todetection section 142 is contacted by an object, the detection result ofthe contact is transmitted to control section 150 in a manner similar tothe above. When the contact of the object is detected in the on state,control section 150 stops application of the voltage to liquid crystallayer 113. As a result, orientation of the liquid crystal material inliquid crystal layer 113 is returned to the state before application ofthe voltage, and the refractive index of liquid crystal layer 113 isalso returned to the state before application of the voltage (offstate).

As described above, in electronic glasses 100 according to the presentembodiment, it is possible to detect the contact of an object and toswitch the focal length of first region 1101 of each of lenses 110.

Although the case where the plan-view shape of diffraction region 117 isa barrel shape has been described in the present embodiment, theplan-view shape of diffraction region 117 is not particularly limited.FIG. 7 is a diagram illustrating another example of a plan-view shape ofdiffraction region 117′. As illustrated in FIG. 7, the plan-view shapeof diffraction region 117′ may be an elliptical shape.

[Configuration of Lens Blank]

Further, each of lenses 110 may be formed integrally with blank portion170. FIG. 8 is a diagram illustrating an example of a configuration oflens blank 200. FIG. 8 is a plan view of lens blank 200. Lens blank 200includes blank portion 170, and lens 110 formed integrally with blankportion 170.

Blank portion 170 is located outside lens 110 so as to surround lens110. A configuration of blank portion 170 is the same as, for example,the configuration of second region 1102 in lens 110. Lens blank 200 isprocessed to a desired shape and a desired size, to obtain lens 110having a desired outer shape and a desired size. In the presentembodiment, lens 110 can be obtained by cutting out blank portion 170along a dashed line illustrated in FIG. 8. An outer shape of blankportion 170 is not particularly limited, and is, for example, a circularshape.

(Effects)

Diffraction region 117 in each of lenses 110 of electronic glasses 100according to the present embodiment includes first diffraction region1173 and second diffraction region 1174. Therefore, in manufacture oflenses 110, it is possible to appropriately and easily dispose theliquid crystal material even on the outer edge part of diffractionregion 117. As a result, liquid crystal layer 113 can be appropriatelyand easily disposed even on the outer edge part of diffraction region117.

Embodiment 2

Embodiment 2 according to the present invention is described withreference to FIG. 9. A lens according to the present embodiment isdifferent from Embodiment 1 described above in position of seconddiffraction region 1174 a of diffraction region 117 a. Morespecifically, in the present embodiment, second diffraction region 1174a is provided in only a part of the outside of first diffraction region1173 a in diffraction region 117 a.

The other configuration of diffraction region 117 a is similar to theconfiguration in Embodiment 1 described above. Accordingly, the lensaccording to the present embodiment is described below while focusing onthe structure of parts different from Embodiment 1 described above. Inthe present embodiment, description in Embodiment 1 described above isappropriately applicable to the structure similar to the structureaccording to Embodiment 1.

Also in the present embodiment, the plan-view shape of diffractionregion 117 a is a so-called barrel shape. The structure of diffractionregion 117 a in the plan-view shape is described below. Outer edge α ofdiffraction region 117 includes first outer edge element α₁ and secondouter edge element α₂ that are opposed to each other in the firstdirection (for example, right-left direction in FIG. 9) orthogonal tothe optical axis direction (direction perpendicular to paper surface ofFIG. 9), and third outer edge element α₃ and fourth outer edge elementα₄ that are opposed to each other in the second direction (for example,top-bottom direction in FIG. 9) orthogonal to the optical axis directionand the first direction. Note that, in the present embodiment, theabove-described first direction is coincident with a short-axisdirection of diffraction region 117 a in the plan-view shape, and theabove-described second direction is coincident with a long-axisdirection of diffraction region 117 a in the plan-view shape.

More specifically, first outer edge element α₁ has a shape followingprotruding strip 1172 a that is provided on the outermost side on oneside (right side in FIG. 9) of diffraction region 117 a in the firstdirection. In other words, the curvature radius of first outer edgeelement α₁ is equal to or slightly larger than the curvature radius ofprotruding strip 1172 a.

In contrast, third outer edge element α₃ is a curved line protruding tothe outside, and connects one end (upper end in FIG. 9) of first outeredge element α₁ and one end (upper end in FIG. 9) of second outer edgeelement α₂. Fourth outer edge element α₄ connects the other end (lowerend in FIG. 9) of first outer edge element α₁ and the other end (upperend in FIG. 9) of second outer edge element α₂. Third outer edge elementα₃ and fourth outer edge element α₄ may be curved lines protruding tothe inside or straight lines.

Third outer edge element α₃ and fourth outer edge element α₄ intersectwith plurality of protruding strips 1172. Plurality of protruding strips1172 intersecting with third outer edge element α₃ is broken off at theposition of third outer edge element α₃. On the other hand, plurality ofprotruding strips 1172 intersecting with fourth outer edge element α₄ isbroken off at the position of fourth outer edge element α₄.

In addition, third outer edge element α₃ and fourth outer edge elementα₄ also intersect with groove spaces 1175 (see FIG. 4B and FIG. 4C)among adjacent protruding strips 1172. Groove spaces 1175 intersectingwith third outer edge element α₃ are broken off at the position of thirdouter edge element α₃. On the other hand, groove spaces 1175intersecting with fourth outer edge element α₄ are broken off at theposition of fourth outer edge element α₄.

Groove spaces 1175 broken off at the position of third outer edgeelement α₃ are open to an external space existing on the outside ofthird outer edge element α₃. On the other hand, groove spaces 1175broken off at the position of fourth outer edge element α₄ are open toan external space existing on the outside of fourth outer edge elementα₄. In other words, broken-off groove spaces 1175 and the external spacecommunicate with each other in a state where the liquid crystal materialconstituting liquid crystal layer 113 is movable.

In the present embodiment, second diffraction region 1174 a is providedat a part on the outer peripheral edge of diffraction region 117 a alongthird outer edge element α₃ and fourth outer edge element α₄.

More specifically, second diffraction region 1174 a located along thirdouter edge element α₃ is provided inside third outer edge element α₃ andoutside solid line β₃ in FIG. 9 in diffraction region 117 a. On theother hand, second diffraction region 1174 a located along fourth outeredge element α₄ is provided inside fourth outer edge element α₄ andoutside solid line β₄ in FIG. 9 in diffraction region 117 a.

Also in the present embodiment, in second diffraction region 1174 a,adjacent groove spaces 1175 (see FIG. 4D) communicate with one anotherthrough communication space 1177 that exists between the ridge lines ofprotruding strips 1172 and second transparent substrate 115.

Accordingly, in second diffraction region 1174 a, liquid crystal layer113 (liquid crystal material) can move among adjacent groove spaces 1175through communication space 1177. In other words, in second diffractionregion 1174 a, liquid crystal layer 113 (liquid crystal material) ingroove spaces 1175 can move not only in a direction along groove spaces1175 but also in direction toward adjacent groove spaces 1175.

As a result, liquid crystal layer 113 (liquid crystal material) disposedin the part along third outer edge element α₃ and fourth outer edgeelement α₄ hardly flows out to the external space outside third outeredge element α₃ and fourth outer edge element α₄. Note that, in the partalong first outer edge element α₁ and second outer edge element α₂,protruding strips 1172 a and 1172 b on the outermost side arerespectively continuous over the entire length of first outer edgeelement α₁ and second outer edge element α₂. Since such protrudingstrips 1172 a and 1172 b serve as weirs, liquid crystal layer 113(liquid crystal material) in the part along first outer edge element α₁and second outer edge element α₂ in diffraction region 117 hardly flowsout to the external space. The other configurations, action, and effectsare similar to those in Embodiment 1 described above.

Embodiment 3

Embodiment 3 according to the present invention is described withreference to FIG. 10. A lens according to the present embodiment isdifferent from the lens according to Embodiment 2 described above indirection of diffraction region 117 b in the lens. More specifically,diffraction region 117 b according to the present embodiment has aconfiguration obtained by rotating diffraction region 117 a according toEmbodiment 2 around the optical axis (clockwise direction in FIG. 10)passing through center O₁ of diffraction region 117 a, by 90 degrees.The other configuration of diffraction region 117 b is similar to theconfiguration according to Embodiment 2 described above. Therefore,detailed description is omitted.

Embodiment 4

Embodiment 4 according to the present invention is described withreference to FIG. 11. A lens according to the present embodiment isdifferent from the lens according to Embodiment 1 described above inconfiguration of diffraction region 117 c. Diffraction region 117 caccording to the present embodiment is described below while focusing ona part different from Embodiment 1.

A plan-view shape of diffraction region 117 c according to the presentembodiment is a semicircular shape. The structure of diffraction region117 c in the plan-view shape is described below. More specifically,outer edge α_(a) of diffraction region 117 c includes first outer edgeelement α_(a1) having a semi-arcuate shape and second outer edge elementα_(a2) having a linear shape. Second outer edge element c connects bothends of first outer edge element α_(a1).

Plurality of protruding strips 1172 of diffraction region 117 c iscoaxially formed around center O₁ of protrusion 1171. Plurality ofprotruding strips 1172 has a semi-arcuate shape. Inner diameters ofplurality of protruding strips 1172 are gradually increased asseparating from center O₁ of protrusion 1171. In addition, distancesamong adjacent protruding strips 1172 are gradually decreased asseparating from center O₁ of protrusion 1171. In the present embodiment,center O₁ of protrusion 1171 and a center (not illustrated) ofdiffraction region 117 c are different from each other.

First outer edge element α_(a1) is a part of a circle around center O₁of protrusion 1171. First outer edge element α_(a1) has a shapefollowing protruding strip 1172 c that is farthest from center O₁ ofprotrusion 1171, among plurality of protruding strips 1172. In otherwords, a curvature radius of first outer edge element ° cal is equal toor slightly larger than a curvature radius of protruding strip 1172 c.

On the other hand, in the present embodiment, second outer edge elementc has the linear shape that connects the both ends of first outer edgeelement α_(a1). Such second outer edge element α_(a2) intersects with(in present embodiment, is orthogonal to) plurality of protruding strips1172. Accordingly, plurality of protruding strips 1172 intersecting withsecond outer edge element α_(a2) is broken off at the position of secondouter edge element α_(a2).

In addition, second outer edge element α_(a2) also intersects with (inpresent embodiment, is orthogonal to) groove spaces 1175 (see FIG. 4Band FIG. 4C) among adjacent protruding strips 1172. Accordingly, groovespaces 1175 intersecting second outer edge element α_(a2) are broken offat the position of second outer edge element α_(a2).

Groove spaces 1175 broken off at the position of second outer edgeelement α_(a2) are open to an external space existing on the outside ofsecond outer edge element α_(a2). In other words, broken-off groovespaces 1175 and the external space communicate with each other in astate where the liquid crystal material constituting liquid crystallayer 113 is movable.

In the present embodiment, second diffraction region 1174 c is providedin at least a part on an outer peripheral edge of diffraction region 117c along second outer edge element α_(a2). In the present embodiment,second diffraction region 1174 c is provided along the entire length ofsecond outer edge element α_(a2). More specifically, second diffractionregion 1174 c is provided inside second outer edge element α_(a2) (sideclose to center of diffraction region 117) and outside solid line β_(a2)(side far from center of diffraction region 117) in FIG. 11 indiffraction region 117 c.

Note that second diffraction region 1174 c may be provided along only apart of second outer edge element α_(a2). The other configurations,action, and effects are similar to those in Embodiment 2 describedabove.

Embodiment 5

Embodiment 5 according to the present invention is described withreference to FIG. 12. A lens according to the present embodiment isdifferent from the lens according to Embodiment 4 described above instructure of diffraction region 117 d. Diffraction region 117 daccording to the present embodiment is described below while focusing ona part different from Embodiment 4.

A plan-view shape of diffraction region 117 d according to the presentembodiment is a partial circular shape larger than a semicircular shape.The structure of diffraction region 117 d in the plan-view shape isdescribed below. More specifically, outer edge α_(b) of diffractionregion 117 d includes first outer edge element α_(b1) having asemi-arcuate shape and second outer edge element α_(b2) having a linearshape.

Plurality of protruding strips 1172 of diffraction region 117 d iscoaxially formed around center O₁ of protrusion 1171. Plurality ofprotruding strips 1172 has an arc shape larger than a semicircular shapein a planar view in the thickness direction. Internal diameters ofprotruding strips 1172 are gradually increased as separating from centerO₁ of protrusion 1171. In addition, distances among adjacent protrudingstrips 1172 are gradually decreased as separating from center O₁ ofprotrusion 1171.

In the present embodiment, center O₁ of protrusion 1171 and a center ofdiffraction region 117 d are different from each other in the plan-viewshape of diffraction region 117 d.

In the present embodiment, second diffraction region 1174 d is providedin a part on an outer peripheral edge of diffraction region 117 d alongsecond outer edge element α_(b2). More specifically, second diffractionregion 1174 d is provided inside second outer edge element α_(b2) (sideclose to center of diffraction region 117 d) and outside solid lineβ_(b2) (side far from center of diffraction region 117 d) in FIG. 12 indiffraction region 117 d. Note that FIG. 13 illustrates Modification 1of Embodiment 5 described above. In a case of diffraction region 117 eaccording to Modification 1 illustrated in FIG. 13, second outer edgeelement α_(b3) is a curved line protruding to the outside of diffractionregion 117 e, in order to enhance visibility of the user. In this case,an inner end edge (solid line β_(b3) in FIG. 13) of second diffractionregion 1174 e is also a curved line protruding to the outside ofdiffraction region 117 e. The other configurations, action, and effectsare similar to those according to Embodiment 4 described above.

APPENDIX

Note that examples of the eyewear include so-called glasses (includingelectronic glasses and sunglasses) and a goggle each including anauxiliary mechanism to improve eyesight of the user such as a visioncorrective lens, and various devices (for example, glasses-type wearableterminal and head mount display) each including a mechanism to presentinformation to a visual field or eyes of the user. In theabove-described embodiments, electronic glasses 100 including pairedlenses 110 for both eyes have been described; however, the eyewearaccording to the present invention is not limited to the aspect. It issufficient for the eyewear to include a configuration that holds theauxiliary mechanism to improve eyesight or the mechanism to presentinformation with respect to eyes by being worn by the user. Accordingly,the eyewear is not limited to of the glasses type mounted on both ears,and may be an apparatus mounted on a head or a single ear. Further, theeyewear may not be the eyewear for both eyes and may be an eyewearacting on a single eye.

Further, in the above-described embodiments, electronic glasses 100including paired temples 140 each including detection section 142 havebeen described; however, the eyewear according to the present inventionis not limited to the aspect. For example, one of the temples may onlyinclude a housing.

The disclosure of Japanese Patent Application No. 2017-020635, filed onFeb. 7, 2017, including the specification, drawings and abstract, isincorporated herein by reference in its entirety.

INDUSTRIAL APPLICABILITY

The lens according to the present invention can be suitably used as alens for eyewear, which includes a liquid crystal material.

REFERENCE SIGNS LIST

-   10 Wiring-   100 Electronic glasses (eyewear)-   110 Lens-   1101 First region (electrically active region)-   1102 Second region-   111 First transparent substrate-   112 First transparent electrode-   113 Liquid crystal layer-   114 Second transparent electrode-   115 Second transparent substrate-   116 Bonding layer-   117, 117′, 117 a, 117 b, 117 c, 117 d, 117 e Diffraction region-   1171 Protrusion-   1172, 1172 a, 1172 b Protruding strip-   1173, 1173 a First diffraction region-   1174, 1174 a, 1174 c, 1174 d Second diffraction region-   1175 Groove space-   1176 Protruding-strip absent part-   1177 Communication space-   1178 Planar part-   1179 Groove-   120 Frame-   130 Front-   131 Rim-   132 Bridge-   133 Nose pad-   140 Temple-   141 Housing-   142 Detection section-   150 Control section-   160 Power supply-   170 Blank portion-   200 Lens blank

What is claimed is:
 1. A lens for eyewear, the lens comprising: a firsttransparent substrate that includes a diffraction region where aplurality of protruding strips and a plurality of grooves are coaxiallyand alternately formed; a second transparent substrate that faces thefirst transparent substrate in a predetermined direction; a liquidcrystal layer that is provided in a space between the diffraction regionand the second transparent substrate; and a first transparent electrodeand a second transparent electrode that apply a voltage to the liquidcrystal layer, wherein: the diffraction region includes a firstdiffraction region and a second diffraction region that is located in atleast a part of a region different from the first diffraction region,and the space includes groove spaces and a communication space, thegroove spaces lying between the grooves and the second transparentsubstrate, the communication space lying between at least a part of theprotruding strips and the second transparent substrate in the seconddiffraction region and communicating between adjacent ones of the groovespaces with one another.
 2. The lens according to claim 1, wherein thefirst diffraction region is located in a portion including a center partof the diffraction region, the second diffraction region is located inat least a part of outside of the first diffraction region, and adistance between each of ridge lines of the protruding strips and thesecond transparent substrate in the second diffraction region is largerthan a distance between each of ridge lines of the protruding strips andthe second transparent substrate in the first diffraction region.
 3. Thelens according to claim 1, wherein the second diffraction region islocated outside the first diffraction region to surround an entirecircumference of the first diffraction region.
 4. The lens according toclaim 1, wherein the second diffraction region is located over an entirecircumference on an outer edge part of the diffraction region.
 5. Thelens according to claim 1, wherein at least a part of a virtual surfacethat is formed by connecting ridge lines of the protruding strips in thesecond diffraction region with each other has a groove shape.
 6. Thelens according to claim 5, wherein the at least a part of the virtualsurface has a groove shape extending along an outer periphery of thelens.
 7. The lens according to claim 6, wherein, of the outer peripheryof the lens, the at least a part of the virtual surface has a grooveshape extending along paired opposite sides crossing a horizontaldirection.
 8. The lens according to claim 5, wherein the virtual surfaceis formed by connecting the ridge lines of adjacent ones of theprotruding strips in the second diffraction region at a shortestdistance, and the virtual surface has a groove shape recessed withrespect to the second transparent substrate.
 9. The lens according toclaim 1, wherein a distance between a ridge line of one of theprotruding strips located on an outer edge of the first diffractionregion and the second transparent substrate and a maximum value of adistance between each of the ridge lines of the protruding strips andthe second transparent substrate in the second diffraction region aredifferent by 0.1 μm to 2 μm.
 10. The lens according to claim 1, whereina distance between an outer edge of the second diffraction region and aninner edge of the second diffraction region is equal to or lower than 2mm.
 11. The lens according to claim 1, wherein at least a part of theplurality of protruding strips located on an outer edge part of thediffraction region is formed such that a distance between each of valleylines among adjacent ones of the protruding strips and the secondtransparent substrate is gradually reduced toward an outer edge of thediffraction region.
 12. The lens according to claim 1, wherein: theliquid crystal material is not substantially disposed between ridgelines of the protruding strips and the second transparent substrate inthe first diffraction region, and the liquid crystal material isdisposed between the ridge lines of the protruding strips and the secondtransparent substrate separated from each other in the seconddiffraction region.
 13. The lens according to claim 1, wherein an outeredge of the diffraction region includes two pairs of opposite sides,opposite sides of one of the two pairs of opposite sides are a part ofan arc, and opposite sides of another of the two pairs of opposite sidesare straight lines or curved lines connecting both ends of oppositesides of the one pair.
 14. The lens according to claim 1, wherein aplan-view shape of the diffraction region is an elliptical shape.
 15. Alens blank, comprising: a blank portion; and the lens according to claim1 formed integrally with the blank portion.
 16. An eyewear, comprising:the lens according to claim 1; a frame that holds the lens; and acontrol section that controls a voltage between the first transparentelectrode and the second transparent electrode to control opticalcharacteristics of the liquid crystal layer of the lens.